One-step thermal polymerization synthesis of nitrogen-rich g-C3N4 nanosheets enhances photocatalytic redox activity

Graphitic carbon nitride (g-C3N4) has attracted enormous attention as a visible-light-responsive carbon-based semiconductor photocatalyst. However, fast charge recombination seriously limits its application. Therefore, it is urgent to modify the electronic structure of g-C3N4 to obtain excellent photocatalytic activity. Herein, we reported a one-step thermal polymerization synthesis of nitrogen-rich g-C3N4 nanosheets. Benefiting from the N self-doping and the ultrathin structure, the optimal CN-70 exhibits its excellent performance. A 6.7 times increased degradation rate of rhodamine B (K = 0.06274 min(-1)), furthermore, the hydrogen evolution efficiency also reached 2326.24 mu mol h(-1) g(-1) (lambda > 420 nm). Based on a series of characterizations and DFT calculations, we demonstrated that the N self-doping g-C3N4 can significantly introduce midgap states between the valence band and conduction band, which is more conducive to the efficient separation of photogenerated carriers. Our work provides a facile and efficient method for self-atom doping into g-C3N4, providing a new pathway for efficient photocatalysts.